接触网在线监测

Overhead Contact System On-line Monitor Technology Based on Wireless Sensor Network

Jiangjian Xie

School of Electrical Engineering Beijing Jiaotong University

Beijing, China 08117331@

Abstract—This paper introduces the development of an effective low cost monitor system to assist the normal function and the maintenance of Overhead Contact System(OCS). The whole system contains a remote monitor centre, some local monitor centres and lots of monitor modules. All the communications are through wireless network. The paper also shows how such a system could be used for OCS monitor, and the detection items are listed. This system can solve the limitations of the inspection van which is used for OCS monitor before, it's of great significance to improve the reliability and safety of high speed electric railway.

Keywords-Overhead Contact System(OCS); Wireless Sensor Network(WSN); On-line Monitor

Yi Wang, Tingting Lu

School of Electrical Engineering Beijing Jiaotong University

Beijing, China

OCS are of great significance to improve the reliability and safety of high speed electric railway.

Conventional method of OCS maintenance is based on periodical detections using inspection van[2]. This method have limitations: it may leave many defects undetected for a relatively long time, also some equipments on the mast couldn't be detected by inspection van. Because of the advantages of wireless communication, wireless communication techniques have also developed rapidly in recent years. Especially with smart low cost wireless communication techniques like Wi-Fi, Bluetooth, and ZigBee are entering into maturity, thus making it possible to develop a wireless sensor network to monitor OCS. The system described in this paper aims to solve these above limitations by introduce an on-line monitor technology to monitor OCS in real time based on wireless sensor network.

II.

PROPOSED SYSTEM STRUCTURE

I. INTRODUCTION

The opening of the Beijing-Tianjin, Zhengzhou-Xi'an, Wuhan-Guangzhou Intercity Railway mark entering high speed railway era in china. Train speed and density are consistently increasing in the last decade. So higher safety and reliability requirements for railway signal, control and infrastructure are needed. The reliability of traction power system(TPS) greatly depends on the reliability of overhead contact system(OCS)[1]. OCS is a no-reserve system, in case the OCS went wrong, this would cause the interruption of the traffic or even became a serious incident. So researches on the monitor technology of

The whole system contains remote monitor centre, local monitor centre and monitor module. Figure. 1 is the schematic of the system, There are two kinds of monitor modules: the majority of monitor modules are continuous monitor modules distributed along the feeding section, which have determined

Figure.1 Schematic of the system

978-1-4244-6255-1/11/$26.00 ©2011 IEEE

locations and exits all the time in the network. The rest are scatted monitor modules,which are dynamic and they could be mobile equipments, they would join the network when they are needed. Every unit has its unique identity and has both data acquisition function and data communication function.

IV. ENERGY SUPPLY OF MODULE

There are many kinds of power supply mode for on-line monitor equipment, such as battery, solar energy, laser energy supply and extraction power from overhead wire etc[4]. The solar energy would be influenced by climatic conditions and

The continuous monitor modules use ZigBee network to lack of long-term maintenance-free operation capability, the communicate, they could only communicate with their laser energy supply isn't suit for outdoor use, so the other two

modes should be considered here. neighbouring monitor modules. So if one module would like to

send some data to the local monitor centre, it has to use the The monitor module can be designed very smart when use monitor modules between them as relays. For scatted battery, it's fit to be installed on the contact line because of the modules,because of their mobility they would use ZigBee or GPRS to communicate. All the modules form the wireless sensor network. Every monitor module consists of two modules: data acquisition module and communication module. In the data acquisition module, there would be some sensors connected to Micro Control Unit(MCU), through which data from the sensors would be processed. Inside the communication module, there is a transceiver for data communication. Figure. 2 is the hardware structure of the monitor module.

Figure. 2 Hardware structure of the monitor module

In every traction substation,there is a local monitor centre, which could communicate with all of the monitor modules directly or indirectly. So local monitor centre could send orders to them and get data from them.

There is one remote monitor centre in maintenance station, the management software based on Internet would be installed in the monitor centre, it could communicate with local monitor centres through Internet. Using Fault Identification Technology and Expert System it could manage and analyze the informations which is collected by local monitor centre to form maintenance tragedy.

III. WIRELESS COMMUNICATION

Wireless sensor network became maturer in recent years, The advantage of it makes it used very often in monitor systems. Considering of the OCS is linear extension, and the transmission distance of ZigBee is limited, so we need design the network topology and data communication protocol to satisfy the OCS on-line monitor. Also the reliability of data link and the system robust should be assured[3]. if nodes fail or radio paths are blocked, data should be automatically re-routed around problems to ensure a seamless flow of information to the monitor centre. Along the feeding sections there would be large quantity of module installed, the self-organizing operation coupled with low-power operation per node should be applied to save manpower to maintain the modules.

less burden. But the battery capacity is limited, so the energy saving tragedy should be used. The module would acquire data all the time in standby mode, and wake up to transmit data to monitor centre just when data acquisition is needed.

To same important nodes, the power supply should be extracted from messenger line to avoid the node failure. Fig. 3 shows the schematic for energy extraction from messenger line, when there is current in messenger line, the energy extraction coil would induce current, through Front-impact protection, Rectifier and filter,DC/DC modules, the output voltage could be got. High voltage isolation and electromagnetic compatibility(EMC) should be proposed. Also the battery group is needed here, The battery group would charge when there is current in messenger line and discharge when no current.

Fig. 3 Schematic for energy extraction from contact line

V. DETECTION ITEMS

By analysing the historical statistics, we concluded the necessary items and characteristic parameters of the monitor OCS, which were showed in table I. Through the detection items we could get useful data, after pre-procession of the data, using the fault diagnosis system in remote monitor centre, we could form a reasonable analyse of the OCS status.

TABLE I. ITEMS AND CHARACTERISTIC PARAMETERS OF ONLINE

MONITORING

Items of on-line Monitor

Characteristic parameters Device

Contact line state parameter

humidity

Current of messenger wire Contact suspension current

distribution grounding wire

VI. CONCLUSION

This paper introduces a low cost system for OCS on-line monitor based on WSN, the system mainly deals with four necessary detection items of OCS, also the communication mode and a module power supply tragedy are described.

REFERENCES

[1] Xie Jiangjian, Wu Junyong, Wu yan, Modeling of Reliability of Traction

Power Supply System Based on Genetic Algorithm[J]，Journal of the China Railway Society,vol.31(4),2009.8: 47-51

[2] K. Liu, W.H. Siew, R.W. Stewart etc,Smart Wireless Railway

Monitoring System[C] 4th IET International Conference on Railway Condition Monitoring (RCM 2008)

[3] M.S. Britton, M.S. Maddison,Towards the reality of intelligent

infrastructure with wireless meshed sensors[C],4th IET International Conference on Railway Condition Monitoring (RCM 2008)

[4] Wu Jintao, Sheng Gehao,Zeng Yi, Design and Development of Power

Supply for Transmission Line Online Monitor Device[J],Electric Engineering,vol.2,2009.2:33-35

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